Jun

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Technically known as the enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of the long tube of our gut, or alimentary 1) ___, which measures about nine meters end to end from the esophagus to the anus. The enteric nervous system is one of the main divisions of the nervous system and consists of a mesh-like system of neurons that governs the function of the gastrointestinal system; it has been described as a second brain for several reasons. The enteric nervous system can operate autonomously. It normally communicates with the central nervous system (CNS) through the parasympathetic (e.g., via the vagus nerve) and sympathetic (e.g., via the prevertebral ganglia) nervous systems. However, vertebrate studies show that when the Vegas 2) ___ is severed, the enteric nervous system continues to function.

In vertebrates, the enteric nervous system includes efferent neurons, afferent neurons, and interneurons, all of which make the enteric nervous system capable of carrying reflexes in the absence of CNS input. The sensory neurons report on mechanical and chemical conditions. Through intestinal muscles, the 3) ___ neurons control peristalsis and churning of intestinal contents. Other neurons control the secretion of enzymes. The enteric nervous system also makes use of more than 30 neurotransmitters, most of which are identical to the ones found in CNS, such as acetylcholine, dopamine, and serotonin. More than 90% of the body’s 4) ___ lies in the gut, as well as about 50% of the body’s dopamine and the dual function of these neurotransmitters is an active part of gut-brain research. Researchers found noticeable improvements in the ability of rats to cope with stressful activity (such as swimming) when diets are supplemented by specific gut microbiota.

The gut-brain axis, a bidirectional neurohumoral communication system, is important for maintaining homeostasis and is regulated through the central and ENS 5) ___ ___ ___ and the neural, endocrine, immune, and metabolic pathways, and especially including the hypothalamic-pituitary-adrenal axis (HPA axis). That term has been expanded to include the role of the gut flora as part of the microbiome-gut-brain axis, a linkage of functions including the gut flora. Interest in the field was sparked by a 2004 study showing that germ-free mice (genetically homogeneous laboratory mice, birthed and raised in an antiseptic environment) showed an exaggerated HPA axis response to 6) ___ compared to non-GF laboratory mice. The gut flora can produce a range of neuroactive molecules, such as acetylcholine, catecholamines, ?-aminobutyric acid, histamine, melatonin, and serotonin, which is essential for regulating peristalsis and sensation in the gut. Changes in the composition of the gut flora due to diet, drugs, or disease correlate with changes in levels of circulating cytokines, some of which can affect brain function. The gut flora also releases molecules that can directly activate the vagus nerve which transmits information about the state of the intestines to the brain. Likewise, chronic or acutely stressful situations activate the hypothalamic-pituitary-adrenal axis, causing changes in the gut flora and intestinal epithelium, and possibly having systemic effects. Additionally, the cholinergic anti-inflammatory pathway, signaling through the vagus nerve, affects the gut epithelium and flora. Hunger and satiety are integrated in the brain, and the presence or absence of food in the gut and types of food present, also affect the composition and activity of gut 7) ___.

Scientists have made an important step in understanding the organization of nerve cells embedded within the gut that control its function — a discovery that could give insight into the origin of common gastrointestinal diseases, including irritable bowel syndrome and chronic constipation and much more. The findings, published in Science, reveal how the enteric nervous system — a chaotic network of half a billion nerve cells and many more supporting cells inside the gut wall — is formed during mouse development. The research was led by the Francis Crick Institute, in collaboration with the University of Leuven, Stanford University, the Hubrecht Institute and the Quadram Institute Bioscience. The work was funded by the Francis Crick Institute, the Medical Research Council and the UK Biotechnology and Biological Sciences Research Council. Often known as the ‘second brain’ for its vast number of 8) ___ and complex connectivity, the enteric nervous system has a crucial role in maintaining a healthy gut. Therefore, understanding how this neural mosaic is organized could help scientists find treatments for common gastrointestinal disorders. During development, a unique and dynamic population of cells known as progenitor cells divide to produce copies of themselves, which can then generate many other types of cells. Using genetic tools, the study labelled individual progenitor cells of the enteric nervous system with unique colors and followed their descendants — also marked with the same color — through development and into the adult animal. By examining the type of cells produced by single progenitors, they could understand their properties. Results showed that some progenitors only produced nerve cells, others only produced nerve-supporting cells called glia, and some produced both. Neurons and 9) ___ originating from the same parent stayed close to each other, forming relatively tight groups of cells. Cell groups that descended from different but neighboring parent cells overlapped like a Venn diagram that could be viewed on the gut surface. Interestingly, this close relationship was maintained by the descendants of single progenitors down through all layers of the gut wall thereby forming overlapping columns of cells. The team explored whether this intricate structure of the enteric nervous system also contributes to nerve cell activity in the gut. According to the authors, a subtle electrical stimulation to the enteric nervous system showed that nerve cells generated by the same parent cell responded in synchrony, and that this suggested that developmental relationships between cells of the enteric nervous system of mammals are fundamental for the neural regulation of gut function. The authors added that now that there is a better understanding of how the enteric nervous system is built and works, it is possible to start looking at what happens when things go wrong particularly during the critical stages of embryo development or early life. Perhaps mistakes in the blueprint used to build the neural networks of the gut are the basis of common gastrointestinal problems. Recent research indicates a possible connection between early gut flora and 10) ___.

Jun

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Michael Gershon MD: Serotonin is a sword and a shield of the bowel: serotonin plays offense and defense. Photo credit: Columbia University Medical School, MD/PhD Program

Michael D. Gershon, is Professor of Pathology and Cell Biology, at Columbia University Medical School and Center. Gershon has been called the father of neurogastroenterology because, in addition to his seminal work on neuronal control of gastrointestinal (GI) behavior and development of the enteric nervous system (ENS), his classic trade book, The Second Brain, has made physicians, scientists, and the lay public aware of the significance of the unique ability of the ENS to regulate GI activity in the absence of input from the brain and spinal cord. Gershon’s demonstration that serotonin is an enteric neurotransmitter was the first indication that the ENS is more than a collection of cholinergic relay neurons transmitting signals from the brain to the bowel. He was the first to identify intrinsic primary afferent neurons that initiate peristaltic and secretory reflexes and he demonstrated that these cells are activated by the mucosal release of serotonin. Dr. Gershon has published almost 400 peer-reviewed papers including major contributions relative to disorders of GI motility, including irritable bowel syndrome, identification of serotonin as a GI neurotransmitter and the initial observation in the gut of intrinsic sensory nerve cells that trigger propulsive motor activity. Dr. Gershon also discovered that the serotonin transporter (SERT) is expressed by enterocytes (cells that line the lumen of the gut) as well as by enteric neurons and is critical in the termination of serotonin-mediated effects.

Dr. Gershon has identified roles in GI physiology that specific subtypes of serotonin receptor play and he has provided evidence that serotonin is not only a neurotransmitter and a paracrine factor that initiates motile and secretory reflexes, but also as a hormone that affects bone resorption and inflammation. He has called serotonin a sword and shield of the bowel because it is simultaneously proinflammatory and neuroprotective. Mucosal serotonin triggers inflammatory responses that oppose microbial invasion, while neuronal serotonin protects the ENS from the damage that inflammation would otherwise cause. Neuron-derived serotonin also mobilizes precursor cells, which are present in the adult gut, to initiate the genesis of new neurons, an adult function that reflects a similar essential activity of early-born serotonergic neurons in late fetal and early neonatal life to promote development of late-born sets of enteric neurons.

Dr. Gershon has made many additional contributions to ENS development, including the identification of necessary guidance molecules, adhesion proteins, growth and transcription factors; his observations suggest that defects that occur late in ENS development lead to subtle changes in GI physiology that may contribute to the pathogenesis of functional bowel disorders. More recently, Drs. Michael and Anne Gershon have demonstrated that varicella zoster virus (VZV) infects, becomes latent, and reactivates in enteric neurons, including those of humans. They have demonstrated that enteric zoster (shingles) occurs and may thus be an unexpected cause of a variety of gastrointestinal disorders, the pathogenesis of which is currently unknown.

Born in New York City in 1938, Dr. Michael D. Gershon received his B.A. degree in 1958 with distinction from Cornell University and his M.D. in 1963, again from Cornell. Gershon received postdoctoral training with Edith Bulbring in Pharmacology at Oxford University before returning to Cornell as an Assistant Professor of Anatomy in 1967. He was promoted to Professor before leaving Cornell to Chair the Department of Anatomy & Cell Biology at Columbia University’s College of P&S from 1975-2005. Gershon is now a Professor of Pathology & Cell Biology at Columbia.

Gershon’s contributions to the identification, location, and functional characterization of enteric serotonin receptors have been important in the design of drugs to treat irritable bowel syndrome, chronic constipation, and chemotherapy-associated nausea. Gershon’s discovery that the serotonin transporter (SERT), which terminates serotonergic signaling, is expressed in the bowel both by enterocytes and neurons opened new paths for research into the pathophysiology of irritable bowel syndrome and inflammatory bowel disease. He has linked mucosal serotonin to inflammation and neuronal serotonin to neuroprotection and the generation of new neurons from adult stem cells. These discoveries have led to the new idea that the function of serotonin is not limited to paracrine signaling and neurotransmission in the service of motility and secretion, but is also a sword and a shield of the gut.

Gershon has teamed with his wife, Anne Gershon, to show that the mannose 6-phosphate receptor plays critical roles in the entry and exit of varicella zoster virus (VZV). The Gershons have also developed the first animal model of VZV disease, which enables lytic and latent infection as well as reactivation to be studied in isolated enteric neurons. The Gershons have also shown that following varicella, VZV establishes latency in the human ENS. Finally, Gershon has made major contributions to understanding the roles played by a number of critical transcription and growth factors in enabling emigres from the neural crest to colonize the bowel, undergo regulated proliferation, find their appropriate destinations in the gut wall, and terminally differentiate into the most phenotypcially diverse component of the peripheral nervous system.

Dr. Michael Gershon has devoted his career to understanding the human bowel (the stomach, esophagus, small intestine, and colon). His thirty years of research have led to an extraordinary rediscovery: nerve cells in the gut that act as a brain. This second brain can control our gut all by itself. Our two brains — the one in our head and the one in our bowel — must cooperate. If they do not, then there is chaos in the gut and misery in the head — everything from butterflies to cramps, from diarrhea to constipation.

Gershon’s groundbreaking book, The Second Brain represents a quantum leap in medical knowledge and is already benefiting patients whose symptoms were previously dismissed as neurotic or it’s all in your head. Dr. Gershon’s research, clearly demonstrates that the human gut actually has a brain of its own. This remarkable scientific breakthrough offers fascinating proof that gut instinct is biological, a function of the second brain. An alarming number of people suffer from heartburn, nausea, abdominal pain, cramps, diarrhea, constipation, or related problems. Often thought to be caused by a weakness of the mind, these conditions may actually be a reflection of a disorder in the second brain. The second brain, located in the bowel, normally works smoothly with the brain in the head, enabling the head-brain to concentrate on the finer pursuits of life while the gut-brain attends to the messy business of digestion. A breakdown in communication between the two brains can lead to stomach and intestinal trouble, causing sufferers great abdominal grief and too often labeling them as neurotic complainers. Dr. Gershon’s research into the second brain provides understanding for those who suffer from gut-related ailments and offers new insight into the origin, extent, and management. The culmination of his work is an extraordinary contribution to the understanding of gastrointestinal illnesses, as well as a fascinating glimpse into how our gut really works.

Jun

26

Currently available Parkinson’s disease (PD) medications are only effective in improving motor deficits caused by the disease. However, the loss of cognitive abilities severely affects the individual’s quality of life and independence. One barrier to developing treatments for the cognitive effects of PD is the considerable variability among patients. As a result, a study must enroll several hundred patients when designing clinical trials to test treatments. Although PD is commonly thought of as a movement disorder, but after years of living with the disease, approximately 25% of patients also experience deficits in cognition that impair function.

According to an article published online in Lancet Neurology (16 June 2017), a newly developed research tool may help predict a patient’s risk for developing dementia and could enable clinical trials aimed at finding treatments to prevent the cognitive effects of the disease. The study combined data from 3,200 people with PD, representing more than 25,000 individual clinical assessments and evaluated seven known clinical and genetic risk factors associated with developing dementia. From this information, a computer-based risk calculator was built that may predict the chance that an individual with PD will develop cognitive deficits. Interestingly, a patient’s education appeared to have a powerful impact on the risk of memory loss. The more years of formal education patients in the study had, the greater was their protection against cognitive decline.

Moving forward, the authors plan to further improve the cognitive risk score calculator. The team is scanning the genome of patients to hunt for new progression genes. Ultimately, it is their hope that the tool can be used in the clinic in addition to helping with clinical trial design. However, considerable research remains to be done before that will be possible. One complication for the use of this calculator in the clinic is the lack of available treatments for PD-related cognitive deficits. Clinicians face ethical issues concerning whether patients should be informed of their risk when there is little available to help them. It is hoped that by improving clinical trial design, the risk calculator can first aid in the discovery of new treatments and determine which patients would benefit most from the new treatments.

Jun

26

NRXN1 and CNTN6 are important during brain development and produce molecules that help brain cells form connections with one another. In addition, the two genes are turned on in areas that are part of the cortico-striatal-thalamo-cortical circuit, a loop of brain cells connecting the cortex to specific regions involved in processing emotions and movement. While copy number variants in NRXN1 have been implicated in other neurological disorders including epilepsy and autism, this is the first time that scientists have linked copy number variants in CNTN6 to a specific disease, Tourette syndrome.

According to an article published online in Neuron(21 June 2017), structural changes have been identified in two genes that increase the risk of developing Tourette syndrome, a neurological disorder characterized by involuntary motor and vocal tics. Although involuntary tics are very common in children, they persist and worsen over time in people with Tourette syndrome. Tics associated with Tourette syndrome appear in children, peak during the early teenage years and often disappear in adulthood. Many people with Tourette syndrome experience other brain disorders including attention deficit disorder and obsessive-compulsive disorder.

For the study, genetic analyses were conducted on 2,434 individuals with Tourette syndrome and compared them to 4,093 controls, focusing on copy number variants, changes in the genetic code resulting in deletions or duplications in sections of genes. The results determined that deletions in the NRXN1 gene or duplications in the CNTN6 gene were each associated with an increased risk of Tourette syndrome. In the study, approximately 1 in 100 people with Tourette syndrome carried one of those genetic variants.

The authors are planning to take a closer look at the mutations using animal and cellular models, and more research is needed to learn about ways in which the genes contribute to development of Tourette syndrome and whether they may be potential therapeutic targets.

Jun

26

Hereditary Angioedema (HAE), which is caused by having insufficient amounts of a plasma protein called C1-esterase inhibitor (or C1-INH), affects approximately 6,000 to 10,000 people in the U.S. People with HAE can develop rapid swelling of the hands, feet, limbs, face, intestinal tract or airway. These attacks of swelling can occur spontaneously, or can be triggered by stress, surgery or infection.

The FDA has approved Haegarda, the first C1 Esterase Inhibitor (Human) for subcutaneous (under the skin) administration to prevent HAE attacks in adolescent and adult patients. The subcutaneous route of administration allows for easier at-home self-injection by the patient or caregiver, once proper training is received.

Haegarda is a human plasma-derived, purified, pasteurized, lyophilized (freeze-dried) concentrate prepared from large pools of human plasma from U.S. donors. Haegarda is indicated for routine prophylaxis to prevent HAE attacks, but is not indicated for treatment of acute HAE attacks. The efficacy of Haegarda was demonstrated in a multicenter controlled clinical trial. The study included 90 subjects ranging in age from 12 to 72 years old with symptomatic HAE. Subjects were randomized to receive twice per week subcutaneous doses of either 40 IU/kg or 60 IU/kg, and the treatment effect was compared to a placebo treatment period. During the 16 week treatment period, patients in both treatment groups experienced a significantly reduced number of HAE attacks compared to their placebo treatment period.

The most common side effects included injection site reactions, hypersensitivity (allergic) reactions, nasopharyngitis (swelling of the nasal passages and throat) and dizziness. Haegarda should not be used in individuals who have experienced life-threatening hypersensitivity reactions, including anaphylaxis, to a C1-INH preparation or its inactive ingredients.

Haegarda received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs to treat rare diseases or conditions.

The basic recipe is one slice of whole wheat or whole grain bread, toasted. Then, cut a ripe avocado in half and pit it. With a spoon, scoop the avocado out of its skin, leaving as little of the flesh as you can. Next, slice it, arrange the slices on the toast. (optional) drizzle a little extra virgin olive oil over the avocado, add seasoning, if you wish. Cut toast in half, in quarters or leave uncut, and eat. Here you see the basic ingredients for avocado toast. Below, are ingredients I have added, to enable you to mix and match, so that this healthy and easy dish stays fresh and new, all summer, indoors or out. Brunch, lunch, beach, backyard, snack or supper. Good with icy beer, chilled white or rose wine, flavored or plain ice water?..just plain delicious with everything, anywhere.

On Saturday we saw a play at one of our theater clubs, where we are patrons, called: Fulfillment Center. I hear it got good reviews; however, sorry to say, neither Jules nor I liked it.

The Big Apple is beautiful these days. We live near Central Park (luckily) and it’s lush these days, with all the rain we’re getting. Everything is in bloom. The park near the Planetarium is gorgeous, as is (Public Library) Bryant Park, near our offices. The Westside Highway is like driving through a park, so many trees have been planted there, plus the wild rose bushes are in full flower now adding to the pleasure of driving down the WSHighway.

The world is in chaos, but this was a relaxing beautiful weekend for us!